Treatment of hydrocarbon oil



Filed May 11, 1938 ATTO R N EY Patented Oct. 1, 1940 UNITED STATES 2,216,691 TREATMENT OF HYDROCARBON OIL Malvin R. Mandelbaum, New York, N. Y., assignor to The Gray Processes Corporation, Jersey City, N. J a corporation of Delaware Application May 11, 1938, Serial No. 207,230

8 Claims.

My invention relates to the treatment of hydrocarbon oil and more particularly to the conversion of relatively heavy hydrocarbon oil to gasoline,

, naphtha, or .rnotor fuel suitable for use in internal combustion engines and the like. My invention relates more especially to the refining of distillates produced by the cracking of hydrocarbon oil under heat and pressure, by passing such distillate while essentially in the vapor phase through a body of adsorbent catalytic material capable of selectively polymerizing undesirable gum-forming and color-imparting unsaturated constituents to compounds of higher boiling points which may readily be separated from the desired product, and as set forth, for example, in U. S. Patents Nos. 1,340,889, 1,759,812, 1,759,813 and 1,759,814, all to Gray.

An object .of my invention is to provide a process of refining distillates of the character set forth by contact in the vapor. phase with a suitable adsorbent catalytic material and having various novel and improved operating features and advantages as compared with the prior art.

A second object of my invention is to provide a novel and improved process of refining distillates of the character indicated by contact in the vapor phase in a plurality of stages with solid adsorbent material, wherein polymers and/or polymer-containing o-il separated in the different stages may be recovered and individually and collectively treated for the recovery and separation of the constituents thereof.

My invention has for further objects such additional improvements in operative advantages and results as may. hereinafter be found to obtain.

In order that my invention may clearly be set forth and understood, I now describe, with reference to the accompanying drawing, various preferred forms and manners in which my invention may be practiced and embodied. In this drawing,

The single figure is a more or less diagrammatic elevational view of apparatus for cracking hydrocarbon oil and for recovering a refined gasoline or motor fuel product from the vapors resulting from such cracking.

Referring now to the drawing, I have illustrated a typical cracking unit comprising in part a cracking furnace I, an evaporator 2 and a bubble tower or fractionator 3. While I have illustrated and will describe hereinbelow, for purposes of illustration and exemplification, a particular form of cracking operation, my invention is not limited to the details of the cracking operation per se, but is readily applicable to the treatment of vapors resulting from various types of oil-cracking operations.

In the particular instance described and shown in the drawing, however, a suitable charging stock, such as a gas oil, a crude petroleum oil, a reduced crude, or any other hydrocarbon oil capable of being cracked to produce low-boiling distillate such as naphtha and/ or gasoline is delivered by a pump 4 and'lines 5 and 6 to the cracking furnace I, wherein the oil is subjected to a high temperature, ordinarily under superatmospheric pressure, and is thereby cracked. The conditions for efiecting such cracking are of course well known to those skilled in the art, 15 and'my invention, at least in its broader aspects, is not limitedto any particular conditions for cracking. However, the oil to be cracked will ordinarily be heated toa temperature of from 800 to 1100 F under a pressure of from atmospheric to as high as 1000 poundsper square 20 inch or even higher, the exact conditions and the time of, contact being chosen according to the character of the particular oil charged and the nature of the results desired.

The cracked products from the furnace 1, con- 2. sisting either entirely or in part of cracked vapors, pass through a transfer line I, wherein may be located a reaction drumor soaking vessel (not shown), to an evaporator 2 where a separation of heavy liquid from gases and vapors takes place. Enough cooling is supplied in the evaporator 2, for example, by admitting thereto through a valved line 8 a portion of the charging stock from the pump 4, to effect a separation of heavy residual constituents which are withdrawn from the bottom of evaporator 2 through a valved outlet line 10. The interior of the evaporator 2 may be provided, as shown, with a plurality of baiiies II, which serve to assist in separating the heavy or residual constituents from the remaining vapors and to prevent undesired entrainment of such constituents in the vapors and gases leaving the evaporator 2.

The remaining vapors and gases from which residual constituents heavier than gas oil have been removed then pass from the evaporator '2 through a vapor line I2 into the lower portion of the fractionator 3, the purpose of which is to rectify or fractionate the vapors to separate and remove therefrom constituents, such as gas oil, which are heavier than the desired final gasoline or naphtha product.

The separated gas oil fraction is removed from the bottom of the fractionating tower 3 through a valved line I3 and may be removed from the system, or, as shown, may be recycled by means of a pump M to the cracking furnace I, preferably at an intermediate point in the course of travel of the charging stock therethrough.

The interior of the fractionating tower 3 is provided with suitable gas-and-liquid contact means, such as plates or trays l5. The cooling necessary to eifect a separation of constituents heavier than gasoline in liquid form from the remaining gasoline vapors and gases maybe variously accomplished, but I prefer to effect this cooling by condensing a portion of the vapors leaving the tower 3 and returning condensate thereby obtained to the tower 3 as a reflux medium therefor.

The remaining gases and vapors leave. the fractionating tower 3 through a vapor line I! having a valve l8 and pass through the line I! to a clay-treating tower 3!] adapted to contain a bed of adsorbent catalytic material, such, for example, as fullers earth-decolorizing clay or the like, as set forth in the patents to T. T. Gray recited 'hereinabove. The adsorbent material is preferably supported within the tower 30 in such manner as to facilitate free drainage therefrom of liquid products of polymerization as well as liquid supplied to the bed of material from an extraneous source, as, for example, from a spray line 3!, and/or any condensate which is separated from the vapors, while traversing the treating bed.

Preferably, the vapors and gases are caused to traverse the bed of treating material in a downward direction in order to facilitate the separation and removal of liquid from the bed of treating material, thereby maintaining the bed in an active condition unhamperedbythe presence of excess quantities of liquid.

According to my invention the treatment of the vapors with adsorbent material is conducted in a plurality of stages. The treated vapors leaving the first clay-treating .tower 30 are passed through a vapor line 32 to asecond clay-treating tower 33 which conveniently may be made identical with the treating tower 30 and similarly contains a bed of solid adsorbent catalytic material supported for free drainage therein.

While I have shown separate treating towers 3! and 33 arranged in series, the treatment of the vapors may be carried out in a single vessel adapted to contain a plurality of separate beds of solid treating material adapted to be traversed serially by the vapors in any desired order. Moreover, the separate towers 30 and 33, when used, or the individual compartments of a tower having a plurality of treating compartments may be provided with suitable valves and connections (not shown) whereby one or the other of the beds of treating material or treating towers may be by-passed whenever desired, and whereby the order in which the vapors traverse the beds may be varied at will.

According to the preferred manner of operating towers located in series, after a suitable period of use, the order .of the towers may be reversed, spent adsorbent being at this time discharged from the tower just .previously first encountered by the vapors .and fresh adsorbent being supplied thereto. The tower containing the fresh adsorbent is then replaced in the system in such manner that it becomes the last tower traversed by the vapors. This method of operating is desirable for the reason that the vapors are caused to traverse the beds in the order of increasing activity, and efficiency of conversion of undesirable constituents is enhanced.

As in the instance of the treating tower 30, the treating tower 33 may be provided with a spray line 34 for introducing into the bed of treating material contained within the tower 33 a suitable liquid washing medium or solvent.

During contact of the vapors with the bed of treating material contained in the towers 3D and 33, the vapors and the treating material may be maintained at a temperature above the normal condensing point of the vapors under the pressure of treatment which is preferably above atmospheric, for example, from 10 to 200 pounds per square inch. The temperature may be and preferably is maintained at such a point, however, that polymers resulting from the contact of the vapors with the treating material and having boiling points higher than the boiling points of the ultimately desired product, separate out from the vapors in liquid form and are removed from the beds of treating material by drainage therefrom. The separation of these higher-boiling polymers ordinarily entails the separation from the vapors of a certain proportion of desired gasoline constituents,' and this is the more marked because it is usually desired to provide a solvent to assist in the removal of the polymers from the beds of treating material. Such solvent may comprise a suitable oil, for example, a previously treated gasoline, supplied from an external or extraneous source to the towers 30 and 33. Where desired, however, a portion of the gasoline constituents themselves may be permitted to condense in the clay-treating tower in order to act as a solvent for removing polymers from the treating material.

Moreover, the gasoline vapors leaving the beds of treating material ordinarily contain a certain proportion of entrained undesired polymers. My invention therefore is in part directed to the more efficient and thorough separation of desired treated gasoline products and the polymers formed as a result of the clay treatment.

I have found that when the treatment of the vapors proceeds in a plurality of stages as, for example, when the vapors are passed first through one clay-treating tower and then through a second clay-treating tower, due in part to differences between the various desired constituents which are polymerized, the polymers resulting in the several stages may difier considerably from each other. While, in the past, when series treatment in a plurality of stages has been effected, it has sometimes been the practice to combine the polymers from the several stages and to dispose of them by delivering them to some earlier point in the system where the temperature is such as to effect a revolatilization of desired constituents and a separation or even a cracking of the polymers themselves, according to one aspect of my present invention the polymers or polymer-containing oils from the several stages of treatment of the vapors are preferably caused to be segregated from each other and may separately be treated for the recovery therefrom of true polymers as well as valuable constituents.

More specifically, as will be made more clear hereinbelow, the relatively strongly polymerized product from a preliminary treating stage may be disposed of by delivering it to a selected portion of the system where the presence of such material will not be objectionable, while the relatively lightly polymerized product separated and recovered'from a subsequent stage may be treated by returning it to a different part of the system. In this manner, the more strongly polymerized products may be prevented from passing to the cracking furnace, while the more lightly polymerized products may be permitted to pass to the cracking furnace. or, where desired, the polymer oils may be flashed to effect a separation of lighter from heavier constituents and the lighter flashed constituents from such flashing operation may be returned to selected points in the system. Such flashing may be carried out in such manner as to produce a residual material consisting to a desired extent of true polymers and constituting-a suitable raw material for chemical synthesis or other manufacture.

In order to effect a separation and removal of relatively high-boiling polymers entrained in the vapors leaving the treating tower 33, these vapors are passed through avapor line 35 to a polymer-separating tower or after-fractionator 36, wherein the vapors are rectified to throw down and condense undesired and relatively high-boiling polymer oil. The fractionator 36 is preferably provided with plates or trays 31, as

well as suitable cooling means, such, for example, as a cooling coil 38 located in the upper portion of the tower 36. A heating or reboiling coil 38' may also be provided in the inner part of the tower 36, as shown. The treated vapors, after rectification, pass fromthe upper portion of the tower 36 through avapor line 39 to a condenser 40, from which condensate and uncondensed material pass to a separator 4| having a valved exit 42 for gases and a valved drain line 43 for condensate, this condensate comprising refined gasoline or naphtha;

Polymers formed during the passage of the vapors through the treating material contained in the treating towerv 33, as well as any solvent oil condensed in or supplied to the tower 33, are removed from the latter through a valved line 50 provided with a pump 5|. The separated and reduced polymer oil collecting in the bottom of the tower 36 is withdrawn therefrom through a valved line 56 for disposal in such manner as may be indicated hereinbelow.

According to one modification of my invention, this polymer oil, which may still contain some constituents which are light enough to constitute a valuable gasoline product, is delivered through a valved line 56, a pump 51 and lines 58, 60 and 6|, to the upper part of the fractionating tower 3 for use as reflux therein. When thus supplied as reflux to the tower 3, this polymer oil is caused to be fractionated in the latter with resultant separation in liquid form of polymers which commingle with the gas oil recovered and removed from the bottom of the tower 3, while the lighter and more valuable constituents pass overhead in vapor form through the vapor line I! and are eventually condensed in the condenser line 40.

It will be obvious to'those skilled in the art that when this polymer oil is delivered to the fractionating tower 3, the polymer contents thereof will pass to 'thecracking furnace l in the gas oil removedfrom the bottom of the fractionator 3 and will be subjected to cracking in the coils'within the furnace I.

If desired, the polymer-containing oil removed from the bottom of the fractionating tower 36 through the line 56 may be delivered through a branch conduit 10 having a pressure-reducing valve H to a polymer flash tower or fractionator 12. The tower I2 is preferably provided interiorly with plates or trays 13, a cooling coil or other cooling means 14 located in the upper portion of the tower 12, and a heating coil 15 located in the bottom of the tower 12. By means of the pressure reduction effected by the valve H, the polymer-containing oil delivered to the tower I2 is caused to be reduced substantially to atmospheric pressure or at any rate to a pressure materially lower than that obtaining in the tower 36, and under the influence of this reduction in pressure the polymer-containing oil is caused to be flashed and the constituents thereof are fractionated or rectified, this action being assisted by the cooling and heating means located within the flash tower 12.

The heavier constituents, comprising principally the true polymers, remain in liquid form and are withdrawn from the bottom of the tower 12 through a valved line 16, while the lighter constituents, comprising naphtha or the like, are withdrawn from the upper portion of the tower 12 through a vapor line 11 and passed to a condenser 18 where normally liquid constituents are caused to be condensed in liquid form. The condensate and any gases that may be present then pass to a separator wherein a separation of liquids from gases occurs, the gases passing out of the separator 80 through a line BI, and the condensate passing out of the separator 80 through a line 82. By means of a line 83 having a valve 84, these constituents may be withdrawn from the system for use as desired. Alternatively, however, by means of a conduit 85 having a valve 86 and a pump 81, this condensate may be delivered either through a valved branch conduit 88 to the upper portion of the fractionating tower 36 or through a valved branch conduit 89 and the inlet 6| to the upper portion of the main fractionating tower 3. As a further alternative, condensate recovered in the separator 80 may be returned through the lines 34 or 3| to the treating tower 33 or the treating tower 3!! or both, as desired.

The polymer-containing oil removed from the bottom of the first treating tower 30 is preferably not returned tothe fractionating tower 3, but, after being withdrawn from the tower 30 through a line 9| having valves 92 and 93, may be delivered to a pump 94 which in turn delivers this polymer-containing oil through the conduit 66 and either the conduit 61 or the conduit 68 to the evaporator 2 or to the transfer line I, as desired. By delivery of the polymer oil to the transfer line I or directly to the evaporator 2 the passage of polymers through the cracking furnace I is avoided and the heavy or residual portions of the polymer oil are largely or entirely removed from the system together with the tar withdrawn from the bottom of the evaporator 2. The introduction of this polymercontaining oil to the transfer line 1 serves the additional purpose of quenching or rapidly cooling the products from the cracking furnace I, thus preventing undesirable continuance of the cracking reaction.

Alternatively, the polymer-containing oil removed from the bottom of the first treating tower 30 may be passed to flash tower or fractionator 12 for treatment therein in the manner described in connection with the polymer-con-' tower 36. For this purpose line I 20, provided with valve I2I, is provided to connect line 9| at a point between valves 92 and 93 with line i0 which in turn communicates with the flash tower or fractionator I2.

The polymer-containing oil withdrawn from the. bottom of treating tower 33 through line 59 may be disposed of inone or more of several ways depending upon its character, which in turn will depend upon the character of the vapors undergoing treatment and the manner of operation of treating tower 33. For example, if the polymers are relatively heavy they may be passed from line 50 through line I22 provided with valve I23. Line I22 connects with line I0 which in turn connects with flash tower or fractionator I2 wherein the polymer-containing oil from treating tower 33 may be subjected to treatment in a manner similar to that described for the. polymer-containing oil from fractionating tower 35 and treating tower 30. Polymercon-taining oil from treating tower 33 may be flashed and fractionated in flash tower or frac-- tionator I2 alone or in conjunction with polymer-containing oils, from other sources in the system. Alternatively, the polymer-containing oil from treating tower 33 may be admixed with the products of conversionin. separator 2 in the manner and for the purpose described in connection with the method of disposal of the polymer-containing oils from treating tower 30. For this purpose line 44, provided with valve 45, is provided connecting line 58 with line QI at a point between valve 93 and pump 94. arrangement either the polymer-containing oil from treating tower or the polymer-contaim ing oil from treating tower 33 maybe passed to admixture with the cracked products in separator 3 by means of conduit 61 or conduit 08. As a further means of disposal of the polymerco-ntaining oil from treating tower 33, it may be passed to the upper part of the fractionating tower 3 for use as reflux therein. This method. of disposal is particularly desirable where the material being treated and the conditions of operation of tower 33 are such that the resulting polymers are relatively free from excessively heavy tarry constituents. For this purpose line 46 containing valve 4! is provided connecting line 50 with line 55. By the connections thusprovided either the polymer-containing oil from treating tower 33, or the polymer-containing oil from fractionating tower 3 .5, or both may be passed through lines 56, 53, '60 and SI for introduction into fractionating tower 3 as reflux. Alternatively, the polymer-containing oil from treating tower 33may be passed through conduit 50 and either branch line 52 or similar line 53 to the fractionator 33, being introduced advantageously to the latter above the point of introduction of vapors from the treating tower 33. The rectification taking place in tower thus serves not only to remove entrained polymers from the vapors leaving the tower 33 but also to effect a separation of desired from undesired constituents present in the polymer oil withdrawn from the bottom of the tower 33.

The foregoing description of various modifications of the process involving various methods of disposal of the polymer-containing oils produced in the operation of the process have been based for purposes of illustration only upon the use of tower I2 as a flash tower. However, it is obvious that the various materials delivered thereto may be so delivered without substantial By this reduction in pressure, the desired separation of polymers from. lighter-constituents being effected by the reboiling means I5 and fractionating means I4; provided in tower 12.

The polymer-containing oil stripped of low boiling constituents desired in the final product which collects in the bottom of tower I2 is withdrawn therefrom through valved line I6.

As a further modification of the invention an intermediate fractionator for the vapors under treatment maybe employed whereby polymers contained in the vapors from treating tower 30 are thoroughly removed, before, passage of the vapors to treating tower 33 with resulting improvement in the life of the catalyst body in treating tower 33. For this purpose intermediate fractionator I02 provided with cooling means II 2, heating or'reboiling means H3, and

plates or trays I I4, may be employed. To effect intermediate fractionation of the vapors in tower I02 line 2;! containing valve 28 is provided connecting line 32 with the lower portion of tower I02, and line I9 is provided connecting the upper portion of tower I02 with line 32 whereby the vapors. inline 32 may be diverted therefrom through line 21, introduced: into tower H32, suitably fractionated therein, withdrawn therefrom and returned, to line 32: through line I9. Valve 29 is provided in line 32 at a point between the connections with lines 2:! and I9 to effect the desired diversion of polymers through line 21. According to. a preferred modification of the invention the fractionation of the vapors in tower I2: is effected in, the presence of polymer-containing oil from treating tower 33. and, optionally, treating tower 30 introduced through line 62 which connects withlines: 50 and I00, the latter in turn being provided wtih valve I0! and connecting with line I20, whereby the polymercontaining oil assists in the-removal of polymers from the vaporsand is itself stripped of low boiling constituents. desired in the product of the process.

The polymer-containing oil stripped of low boiling constituents desired in the final product. which collects inthe bottom of tower I02, is withdrawn; therefrom through valved line I03. This material mayvbe wit'hdrawn from the system for any suitable, further treatment. Alternatively, all, ora; portion. of this polymer-containing oil may be diverted from line I03 through valved line provided with pump 49. Line 48 connects line I03:with line fifi'whereby the polymer-containing oil from tower I02,may be passed through lines 48 and B6; to either or both of conduits 61 and 68 for admixture with the cracked products in the transfer line I or in the separator 2' in the manner described in connec tion with the disposal of polymer-containing oil from tower-30 or from tower-33.

It will be apparent from the above description that within the scope ofmy invention various modifications may beemployed for the treatment of the vapors and disposal of the polymercontaining oils depending upon the material under treatment and the conditions of operation. For example, the polymer-containing oil from treating tows-r30 may be distilled in tower I2 in the manner described while the polymer-con taining oil from treating tower 33 is admixed with the cracked products in separator 2 or in transfer line I. At the same time in this modification the polymer-containing oil from fractionating tower- 35 maybe introduced into the upper portion of fractionating tower 3 as reflux therefor,

and the low-boiling constituents distilled .from the polymer-containing oil in tower IZ may be passed through lines 85, 89; and 6| for introduction into fractionating tower 3 as reflux.

In another modification of the process the polymer-containing oil from treating tower 30 may be admixed with the cracked products in transfer line I or in separator 2 while the polymer-contaimng oil from treating tower 33 alone or in admixture with the polymer-containing oil from fractionating tower 36 may be'introduced into the upper. portion offractionating tower 3 as reflux therefor.

In still another modification of the process the polymer-containing oil from treating tower 30 and treating tower 33 may beconjointly'distilled in .tower 12. In this method of operation the polymer-containing oil from fractionating tower 36 also 12 for distillation therein or may be introduced into tower 30 as reflux. The vapors distilled from the oil introduced, into tower 12 may be returnedto the system for further treatment by passage through a treating tower'containing solid adsorbent catalytic materiaL. For example, the vapors may be condensed and the condensate thus obtained introduced into tower 3 as reflux.

In still another modification of the invention tower Hi2 may be employed to fraction'ate the vapors from treating tower 36 prior to their introduction into treating tower 33 while polymercontaining oil from treating tower 33 is introduced into tower I62 for reboiling therein, optionally in conjunction with polymer-containing oil from treatingtower 30.

It will be seen that my process provides for a considerable improvement in flexibility and economy of operation, particularly when the vapor phase treatment of the gasoline hydrocarbons with adsorbent material is carried out in a plurality of stages located in series'along the path offlowof the vapors and. that my invention further provides for the'disposal of polymer-cons tainingoils drawn from the various stages in a manner best suited to the characteristics thereof.

While I have described my invention hereinabove with respect to various illustrative examples and embodiments it will be obvious to those skilled in the art that my invention is not limited to the details of such illustrative examples or embodiments, but may variously be practiced and embodied within the scope of the claims hereinafter made.

This application is a continuation-in-part of my prior application Serial No. 713,437, filed March 1, 1934, now Patent No. 2,123,194, dated July 12, 1938.

I claim:

1. In the method of producing refined gasoline from higher boiling hydrocarbon oil wherein said higher boiling hydrocarbon oil is subjected to cracking conditions, the cracked products are separated into vapors and residue, and the vapors are subjected to fractionation to separately condense constituents above the gasoline boiling range, the improvement which comprises subjecting uncondensed vapors from said fractionation to contact with solid adsorbent catalytic material in a plurality of successive treating stages to effect polymerization of unstable unsaturated constituents thereof to higher boiling polymer products under conditions effective to cause condensation of polymers thus formed, removing polymer-containing oil from an early treating stage and subjecting it to distillation in a separate zone removed from the flow of the vapors may be passedthrough line 10 into tower" undergoing treatment to separate it into a fraction containing constituents lying within the gasoline boiling range and a fraction containing higher boiling polymer constituents, admixing gasoline constituents thus obtained with said vapors prior to contact thereof with solid adsorbent catalytic material, removing polymer-containing oil from a later treating stage and passing polymers thus obtained to the zone wherein the cracked products are separated into vapors and residue, fractionating the vapors after passage through said later treating stage to effect condensation of a polymer-containing oil, and pass ing said polymer-containing oil to admixture with said vapors during said first-mentioned fractionation.

In the method of producing refined gasoline from higher boiling hydrocarbon oil wherein said higher boiling hydrocarbon oil is subjected to cracking conditions, the cracked products are separated into vapors and residue, and the vapors are subjected to fractionation to separately condense constituents above the gasoline boiling range, the improvement which comprises subjecting uncondensed vapors from the fractionating zone to contact with solid absorbent catalytic material in a plurality of successive treating stages to effect polymerization of unstable unsaturated constituents thereof to higher boiling polymer products under conditions effective to cause condensation of polymers thus formed, removing polymercontaining oil from an early treating stage and passing polymers thus obtained to the zone wherein the cracked products are separated into vapors and residue, fractionating the vapors after passage through a later treating stage to condense therefrom a polymer-containing oil, and admixing said last-mentioned polymer-containing oil with said vapors during said first-mentioned fractionation.

3. In the production of refined gasoline wherein hydrocarbon vapors including gasoline constituents are passed through a fractionating zone to condense separately constituents above the gasoline boiling range, and remaining gasoline vapors are subjected to contact in a plurality of successive treating zones with solid adsorbent catalytic material capable of polymerizingobjectionable unsaturates, the steps comprising Withdrawing polymer-containing oil from the final treating zone and an earlier treating zone, distilling said withdrawn polymer-containing oil in a separate zone removed from the flow of vapors undergoing treatment to separate it into a fraction containing constituents boiling within the gasoline boiling range and a fraction containing higher boiling polymer constituents, admixing gasoline constituents thus obtained with said vapors prior to cont-act thereof with solid adsorbent catalytic material, fractionating the vapors after passage thereof through the final treating stage to condense therefrom a polymercontaining oil, and passing said last-mentioned polymer-containing oil to said separate distillation zone for treatment therein with said firstmentioned polymer-containing oil.

4. In the production of refined gasoline wherein hydrocarbon vapors including gasoline constituents are passed through a fractionating zone jectionable unsaturates, the steps comprising Withdrawing polymer-containing oil from the final treating zone and an earlier treating zone, distilling said withdrawn polymer-containing oil in a separate zone removed from the flow of vapors undergoing treatment to separate it into a fraction containing constituents boiling within the gasoline boiling range and a fraction containing higher boiling polymer constituents, admixing gasoline constituents thus obtained with said vapors prior to contact thereof with solid adsorbent catalytic material, fractionating said vapors after passage thereof through said final treating zone to condense therefrom a poly- 'mer-containing oil, and admixing said last-men'- tioned polymer-containing oil with said vapors during said first-mentioned fractionation.

5. In the production of refined gasoline wherein hydrocarbon vapors including gasoline constituents are passed through a frac-tionating zone to condense separately constituents above the gasoline boiling range, and remaining gasoline vapors are subjected to con-tact in a plurality of successive treating. Zones; With solid adsorbent catalytic material capable of polymerizing objectionable unsaturates, the steps comprising withdrawing "polymer-containing oil from the final treating zone and an earlier treating zone, distilling said withdrawn polymer-contaim'ng oil in a separate zone removed from the flow of vapors undergoing treatment to separate it into a fraction containing constituents boiling within the gasoline boiling range and a fraction containing higher boiling polymer constituents, condensing at least a portion of the gasoline constituents distilled from said polymer-containing oil in said separate zone, and introducing condensate obtained by said lastmentioned condensing operation as reflux liquid into the zone of said first-mentioned fractionation of said vapors.

6. In the production of refined gasoline wherein gasoline vapors are subjected to contact with solid adsorbent catalytic material capable of polymerizing objectionable unsaturates ina plu' rality of successive treating stages, the steps comprising passing said vapors through a frat:-

tionating zone after contact with solid adsorbent catalytic material and prior to passage thereof to the final treating stage to effect condensation and separation of polymers from said vapors, withdrawing condensate 'oil contaimng polymers formed in said final treating stage and introducing the same into said fractionating 'zone, and reboiling polymer-containing oil in said frac tionating zone to strip therefrom gasoline constituents as vapors- 7 In the production of refined gasoline where"- in gasoline vapors are subjected to contact with solid adsorbent catalytic material capable of polymerizing objectionable unsaturates in a plurality of successive treating stages under conditions effective to cause condensation of polymers thus produced, the steps comprising passing said vapors through a 'fractionating zone after contact with solid adsorbent catalytic material and prior to passage thereof to the final treating zone to 'eifectco n'de'nsat'ion and separation of polymers from said vapors, withdrawing polymercontaining oil from said final treating zone and introducing same into said fractionating zone, and reboiling poIymerQcQnt-aining oil in said fractionating zone to strip therefrom gasoline consutu'ents as vapors.

8. In the production of refined gasoline wherein gasolir'ie vapors are subjected to contact with solid adsorbent catalytic material capable of polymerizing objectionable unsaturates in a pluralityof successive treating stages, the steps comprising passing said vapors through a fractionat'ing Zone arte'r Contact With solid adsorbent catalytic material and prior 'to passage thereof to the final treating stage to effect condensation and "separation or polymers from said vapors, Withdrawing polymer cdntaining oil from. said final treating stage and from a treating stage prior to said fradti'ona' "lig zone and introducing s me into said fractidrlati ng zone, andreboiling polymer -containing oil in said fractionatinlg zone to strip therefrom gasoline constituents as vapors. I

MALVIN R. MANDELBAUM. 

